Light emitting diodes (LEDs), owing to their long service life, high efficiency, low energy consumption and small size, are widely applied in daily life and tend to be important products in modern lighting development.
For LED chips with non-conductive substrates, e.g., sapphire, thermal conductivity of the substrates is low, resulting in high temperature of PN junctions in lateral LEDs. To solve heat dissipation, a flip-chip structure with improving light emitting efficiency is proposed. To further solve light extraction, the flip-chip structure substrate is further lifted off to form a thin film flip chip. As applications develop, to improve chips' photoelectric conversion efficiency, new attempt is made to combine high-voltage chip structures and thin-film flip chips.